When asked why he still believes Canada is in deficit, Trudeau said because "the Parliamentary Budget Officer, in his analysis, said that we were." In July, the PBO projected the government would not balance the books this year.

'You either know and won't say, or you don't know'

But it was an exchange on the Liberals' spending that was later pounced on by both Tories and the NDP.

"What's the dollar value of all your new spending promises?" Murphy asked.

The Liberal leader said they were about two-thirds of the way through to the commitment to a $10-billion deficit in year one, two, and "less in year three."

"So, how much new spending have you announced thus far?"

"A fair bit. We have a full costing coming out. No, we're the first party that put out a fully costed framework that said three years of deficits, plus a balanced budget," he said.

Murphy was unsatisfied with the answer.

"You either know and won't say, or you don't know," the journalist said.

Trudeau said a "properly costed platform" would be released once all the promises have been made, and told Murphy he could tabulate the numbers himself on the Liberal website.

"I'm more focused on actually talking about what we're going to do right away for Canadians than sitting there with a calculator which, you know, you guys can do," he said.

The NDP released its fiscal plan before the leaders' debate last week and called on Liberals to do the same. But Trudeau asserts his was the first party to publicly release a fiscal framework. The Tories are basically running on their budget from April.

Trudeau said Conservative charges that Liberal plans would result in a $24.7-billion shortfall were "completely wrong," and denied the party has already blown through $10 billion in promises.

When pressed his revenue streams beyond raising taxes on the wealthiest Canadians, Trudeau said he would have more to announce in the coming weeks, but said there would not be more taxes.

"We could put this off for a few weeks and we can have more conversation once I have…" Trudeau said.

Murphy cut in: "Well, we can't put it off too much longer. The election's in four weeks."

"In four weeks and therefore we can talk again in two weeks… two or three weeks, and I'd be glad to highlight all the elements in it," the Liberal leader said.

Tory, NDP war rooms go on offensive

NDP press secretary James Valcke released a Vine of Trudeau and described the leader as contradicting himself in six seconds.

"Justin Trudeau is promising years of deficits and he's already maxed out his credit card — half way through this campaign he's run out of money and not made a single commitment to healthcare or education," the NDP release charged.

And on the right, Tories accused Trudeau of ducking questions about how he will pay for spending pledges.

Matt Wolf, who works in the Conservative war room, has already tweeted two clips from the interview that could find their way into attack ads.

In the 2008 election, Murphy's interview with then-Liberal leader Stephane Dion sparked controversy after CTV aired an unedited version that showed Dion struggling to understand an awkwardly phrased question. Dion asked the journalist to restart the interview three times.

The clip was also aired nationally on "Mike Duffy Live" — several times — and sparked debate about Dion's comprehension of the English language just as the campaign was coming to a close.

The Canadian Broadcast Standards Council later ruled that CTV Atlantic violated industry codes by airing the false starts, and behaved in a "discourteous and inconsiderate" manner.